This question touches a nerve. In my very first job in IT, I was tasked to
(re)write a program that tabulated the contents of a large master file. The
idea was to examine each record and record its 'type' in a table. This was
1978. I was fresh out of programming school. Sort of starry eyed, I guess.

I found a manual with instruction timings and settled on the this sequence to
increment each bucket:
L R1,COUNTER
LA R1,1(,R1)
ST R1,COUNTER
I can tell you that the program ran like a bat out hell. I was an application
programmer trainee who heard from the sysprog staff that they used my program
to benchmark new hardware! After I had moved on to other opportunities, I
reflected on a huge oversight. In 1980--before the advent of XA--this logic
would fail utterly beyond 16M records in any bucket. I never heard what
happened, but I came to believe that outright speed was the wrong metric. Be
careful to set the right goal.
.
.
J.O.Skip Robinson
Southern California Edison Company
Electric Dragon Team Paddler
SHARE MVS Program Co-Manager
323-715-0595 Mobile
626-543-6132 Office ⇐=== NEW
robin...@sce.com
-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of
Brian Chapman
Sent: Monday, August 12, 2019 5:48 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: (External):Instruction speeds
Hi everyone,
I did some searching, but I didn't find anything that really discussed this on
the topic that I'm interested. Is there anything published that compares the
cycle times of the most used instructions?
For example; moving an address between areas of storage. I would assume that
executing a LOAD and STORE would be much quicker than executing a MVC.
Or executing a LOAD ADDRESS to increment a register instead of ADD HALF WORD.
Or does this really matter as much as ordering the instructions so they are
optimized for the pipeline?
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